Is BIG-PLUS An International Standard?
Jack Burley
reproducing spindles and tooling. Access to this information and gaging is well protected by BIG and is only provided to those companies who acquire a license agreement, mostly to protect the integrity of the system, which uses very close tolerances in order to function at its designed
performance level.
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The popularity of BIG-PLUS has surged over the past 10 years as many shops have tried the system and have witnessed for themselves the huge benefits in higher performance and accuracy over standardized taper contact tooling systems, such as CAT or
S P I N D L E S Y S T E M DUA L CON T AC T
Buyer Beware: This system has not been standardized by any governing body. If you purchase cheap dual contact tooling after being told by a supplier that it will work just as good as the original for half the price, you risk unsatisfactory performance and/or damage to very expensive spindles. Here’s why. More and more, we are asked this fairly simple question from shops who want to purchase BIG-PLUS dual contact tooling from sources other than us. One would certainly think that this must be the situation, given that more than 100 of the world’s top- selling machine tool builders have adopted the BIG-PLUS spindle system as their own standard. The truthful answer to anyone who asks is that this system has not been standardized by any governing body such as ISO, DIN, JIS, or ASME. BIG Daishowa, the original developer of this system and a major reason that it has been so widely accepted throughout the world, still holds all of the proprietary information and, more importantly, the grand master gages that are used for
PROPER FIT • Dual contact
of taper and flange face after clamping
FLANGE CONTACT ONLY Limited or No Taper Contact • Poor runout accuracy • Severe chatter and vibration • Spindle damage
TAPER CONTACT ONLY No Flange Contact • Features of BIG-PLUS are voided • Works same as taper-only contact tooling
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